Preparation of ethylenesulfonic acid



' ethanedisulfonyl chloride. Neither Patented May 20, 1952 PATENT OFFICE PREPARATION OF ETHYLENESULFONIC ACID John A. Anthes, Springdale,

ignors to American Cyanamid Darien, Conn., ass Company, New Maine No Drawing.

Serial 7 Claims.

This invention relates to a process for the preparation acid.

In the past ethylenesulfonic acid has been prepared by a multi-step process culminating in the pyrolysis of beta-acetoxyethanesulfonic acid. It

has also been prepared by hydrolysis of of these procnew and improved of ethylenesulfonic esses has been entirely satisfactory.

It is an object vide a simple one-step process of ethylenesulfonic acid.

Another object of the present invention is to provide a process for the preparation of ethyleneand commercially for the preparation sulfonic acid which is simple practicable.

The above and other objects are attained by dehydration of isethionic acid.

The invention will be described in greater detail in conjunction with the following specific examples in which the proportions are given in parts by weight. It should be understood that the invention is in no sense limited to the details of the examples which are merely illustrative.

EXAMPLE 1 20 parts of sodium isethionate (0.14 mol.) 50 parts of pyrophosphoric acid (0.28 mol.)

The sodium isethionate and the pyrophosphoric acid are mixed together and heated over oil in a vacuum distillation apparatus. Collection of distillate is started at 90 C. at 0.7 mm., most of the distillate coming oif at 107 C. at 0.5 mm. Th distillation is stopped when the head temperature begins to fall. The pot temperature is about 220230 C.

9 parts of the amber-colored distillate are re distilled at 93 C. at 0.07 mm., and 7.5 parts of a nearly colorless product are obtained. This represents an overall yield of 51%. The index of refraction of the ethylenesulfonic acid obtained is 1.4505 at 25 C. and its neutral equivalent, 112. The theoretical neutral equivalent for ethylenesulfonic acid is 108.

Upon exposure for 24 hours to light from a quartz mercury ethylenesulfonic acid product polymerizes to a brown water-soluble polymer which becomes rubbery after 66 hours but is still water-soluble.

EXAMPLE 2 296 parts of sodium isethionate (2 mols.) 204 parts of 96% sulfuric acid (2 mols.) 200 parts of pyrophosphoric acid 100 parts of phosphorus pentoxide of the present invention to pro- York, N. Y.,

and James a. Dudley,

a corporation of Application March 18, 1948,

The above ingredients were mixed together in a suitable vessel equipped with means for agitation, temperature indicating means, and a distillation head with condenser and receiver ar- 5 Found temperature increases ranged for vacuum distillation. The vessel 18 jacketed and heated electrically. Collection of distillate is started continued about temperature drops v mm. Throughout the heating period, the pot C. to 233 C. and the jacket temperature, from 232 C. to 264 C. 175 parts of crude distillate are obtained. This is redistilled at 0.5 mm., d 142 parts of a product boiling at 100-l05 C. at 0.5 mm. are obtained. This represents a yield of 66% of the theoretical.

p EXAMPLE 3 Part A 74 parts of sodium isethionate (0.5 mol.) 51 partsof 96% sulfuric acid (0.5 mol.) 7 259 parts of methanol as an aqueous solution parts of 72.3% solution of isethionic acid- (0.5

mol.) H w 142 parts of phosphorus pentoxide (1 mol.)

The phosphorus pentoxide is added to the isethionic acid with sufficient cooling so that the temperature does not rise above C. The resulting solution is heated by means of an oil bath at 250 C. in a vacuum distillation apparatus at 0.8 mmpressure. Distillation is stopped when the pot temperature reaches 233 C. (bath temperature 254 C.). 42 parts of the crude distillate, which is a brownish color, are redis- The main fraction which comes off at 96-l00 C. is again redisproduct boiling at 103 C.

Upon analysis the final product is found to have the following composition:

Percent Percent Percent C E S Calculated for CqH4SO; 3. 73 29.7

ide according to the equation NaHSOa cert 11, nocnzcmsoma If desired, an alkali metal salt of isethionic acid, i. 13., sodium isethionate, potassium isethio- 7 ate, et may be used as the starting material ited thereto.

Any acidic dehydrating agent Serial and now U; S

isethionic acid.

6. A process according to claim 1 isethionic acid is prepared in situ by heating an JOHN A. ANTHES. JAMES R. D DLEY.

,REFERENCES CITED The following references are of record in the file of this patent.

UNITED STATES PATENTS Number Name Date 2,243,331 De Simo May 27, 1941 FOREIGN PATENTS Number Country Date 406,788 Great Britain V of 1934 OTHER REFERENCES Murray: J. Am. Chem. Soc., vol. 62, pp.

1230-1234, May 1940.

Matignon et al.: Bull. Soc. Chim. France, vol. 2, 5th Sen, part 2, p. 1170 (1935).

Organic Chemistry of Sulfur by Suter, 1944 edition, p. 13 

1. A PROCESS WHICH COMPRISES HEATING ISETHIONIC ACID AT A TEMPERATURE OF FROM 200* TO 250* C. AND AT A PRESSURE BELOW 3 MM. OF HG, AND DISTILLING OFF THE ETHYLENESULFONIC ACID OBTAINED AS IT IS FORMED. 